JPH11344341A - Parallel flat plate vibration gyro and parallel flat plate vibration gyro device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a parallel flat plate vibration gyro and parallel flat plate gyro device which can obtain a high piezoelectric signal, without canceling generated voltages if the expansion-shrinkage is reverse at the side face portions of parallel flat plates when the parallel flat plats to be a detector are deformed. SOLUTION: A stainless base 4 of the vibration gyro 1 is a square column and mutually orthogonal through-holes 10, 7 are bored into the top and bottom of the base 4, thereby constituting parallel flat plates 3, 2. A Ti film 13 is formed by the sputtering, etc., on the outer side faces of the parallel flat plates 3, 2, PZT film 14 is formed on the entire outer surface of the Ti film 13, first Al electrode film 15 to fourth Al electrode film 18 each having a thickness of several micrometers and the same area are formed respectively as an upper and lower pairs on the PZT film 14, the first and second electrode films 15, 16 are separated to reduce the area of the electrode film, compared with the conventional one, thereby increasing the generated (piezoelectric) voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel plate type vibrating gyroscope and a parallel plate type vibrating gyroscope having high detection sensitivity.

[0002]

2. Description of the Related Art As a conventional vibration gyroscope (hereinafter referred to as a vibration gyroscope), a tuning fork type shown in FIG. 13 and a sound piece type shown in FIG. 14 are known.

In a tuning fork type vibrating gyroscope 21, as shown in FIG. 13, a pair of driving piezoelectric ceramic plates 23 are provided upright at both ends of a connecting plate 22 so that their planes face in the X direction in the figure. Are located in A piezoelectric ceramic plate 24 for detection is integrally erected on the center of the upper end of the piezoelectric ceramic plate 23 for driving, and is arranged so that its plane faces the Y direction in the figure. Note that the X direction and the Y direction are orthogonal to each other. And
By applying an alternating voltage to the lower piezoelectric ceramic plate 23 for driving, the piezoelectric ceramic plate 23
Vibrates in the direction. In this vibration state, the vibration gyro 21
When the rotation around the Z-axis is applied to the detection piezoelectric ceramic 24, the detection piezoelectric ceramic 24 is distorted, and the voltage generated at that time is detected, whereby the force applied to the detection piezoelectric ceramic 24 can be detected. This force is the Coriolis force Fc
And is generally represented by the following equation.

Fc = 2mV × ω (1) where m is the mass of the vibrating gyroscope 21, V is the vibrating speed of the vibrating gyroscope 21, and ω is the angular velocity of the vibrating gyroscope 21 around the Z axis. If the mass m and the vibration velocity V are known, the angular velocity ω can be derived.

[0005] A vibrating gyroscope 25 of a sound piece type is shown in FIG.
As shown in FIG. 7, a square-pole vibrator 26 made of a constant elastic metal is provided, and a pair of piezoelectric ceramic plates 27 for driving are attached to the side surfaces of the vibrator 26 opposite to each other by 180 degrees. (Only one is shown in the drawing).
A pair of piezoelectric ceramic plates for detection 28 are adhered to the other side surfaces (only one of them is shown in the drawing).
The vibrating gyroscope 25 vibrates the resonator element vibrator 26 in the X and anti-X directions by applying an alternating voltage to the driving piezoelectric ceramic plate 27. In this state, when rotation about the Z-axis is applied to the vibrating gyroscope 26, the detecting piezoelectric ceramics 2
8 is distorted, and by detecting the voltage generated at that time, it becomes possible to detect the Coriolis force acting on the detecting piezoelectric ceramics 28.

By the way, bulk PZT (ceramic made of a solid solution of lead zircon / titanate: lead titanate, lead zirconate) is provided on the driving piezoelectric ceramic plates 23 and 27 and the detecting piezoelectric ceramic plates 24 and 28. Is used.

However, bulk PZT as described above
However, there is a problem that it is difficult to make the bulk itself thinner, and it is difficult to reduce the size of the entire vibrating gyroscope. Also, when a vibrating gyroscope is configured by sticking a piezoelectric ceramic plate, such as a vibrating gyroscope of a sound piece type, the sticking process increases and
There is a problem that adhesion accuracy, that is, position accuracy is poor. Therefore, there is a problem that it affects detection sensitivity and the like and that it is difficult to accurately manufacture a homogeneous product.

Further, when the vibrator is a three-dimensional structure,
There is a case where it is difficult to attach the bulk PZT to an arbitrary place, and there is a problem that the attachment place is limited. The Coriolis force Fc, as shown in the above equation (1), increases the Coriolis force when the mass m of the vibrating gyroscope is increased. As a result, the amount of distortion of the piezoelectric ceramic for detection increases. The detection voltage also increases. That is, the detection sensitivity is increased. For this reason, it is preferable that the mass of the vibrating gyroscope is large in order to obtain detection sensitivity. However, in the case of a vibrating gyro using bulk PZT, bulk PZT
Unless the base material constituting T is made large, there is a problem that the mass cannot be increased, and there is a limit in increasing the detection sensitivity.

The Coriolis force Fc, as shown by the above equation (1), increases the Coriolis force as the vibration velocity V increases, and as a result, the amount of distortion of the detecting piezoelectric ceramic increases. Also, the detection voltage increases and the detection sensitivity increases. However, in the case of a tuning fork type vibrating gyroscope, for example, in the case of a tuning fork type vibrating gyroscope, if the bulk PZT base material is thinned, the rigidity is reduced, so that it becomes easy to be twisted and does not vibrate accurately, The distortion for detecting the element is also in a state in which the element is twisted, which causes a problem that accurate detection cannot be performed.

The applicant has proposed a vibration gyro 31 having a structure shown in FIG. 10 which can be reduced in size, is resistant to twisting, and can increase the detection sensitivity. The vibrating gyro is provided with through holes 34 and 35 orthogonal to each other at a lower end (fixed end) side and an upper end (free end) side of a quadrangular prism-shaped elastic metal 30, respectively.
A second parallel plate portion 33 is formed. As shown in FIG. 11, a titanium film 38 is formed on the outer surfaces of the first parallel plate portion 32 and the second parallel plate portion 33, and a PZT thin film 36 is formed on the titanium film 38. The first parallel flat plate portion 32 is used as a driving portion for applying vibration,
The side of the parallel plate part 33 is a detection part.

The vibrating gyroscope 31 having the above-described structure is
As shown in FIG. 10, on the PZT thin film 36, the P
A plate-like electrode 37 is further formed of aluminum or the like so as to be slightly smaller than the size of the ZT thin film 36, and a lead wire (not shown) is directly connected to the electrode 37 to form a first parallel plate portion as a driving unit. 32, a voltage is applied to apply vibration, and the second parallel flat plate portion 33 serving as a detection portion
The voltage generated in the ZT thin film is detected via a lead wire (not shown) directly connected to the electrode 37.

[0012]

According to the above arrangement,
When the second parallel plate portion 33 serving as the detection portion is deformed, the deformation has a waveform as shown in FIG.

However, the upper side of the second parallel plate portion 33,
Since the expansion and contraction of the PZT thin film 36 are reversed between the lower side and the lower side, the voltages generated in the respective portions obtained by the respective deformations of the upper and lower sides are reversed. As a result, as shown in FIG.
If the common electrode 37 is provided in a portion where the expansion and contraction of the upper side and the lower side of the T thin film 36 are opposite, the generated voltage is canceled out, and the output obtained from the electrode 37 cannot be sufficiently obtained. was there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and when the parallel plate portion serving as the detecting portion is deformed,
Provided are a parallel plate type vibrating gyroscope and a parallel plate type vibrating gyroscope capable of obtaining a large piezoelectric signal without canceling out the generated voltage even if the expansion and contraction are reversed in each side portion of the parallel plate portion. It is in.

[0015]

In order to solve the above-mentioned problems, the invention according to claim 1 has first to fourth side surfaces in a circumferential direction, and the first and third side surfaces are provided. The second side surface and the fourth side surface include a quadrangular prism-shaped elastic metal located at positions opposite to each other by 180 degrees, and a fixed end side of the elastic metal includes:
A through hole penetrating from the first side surface to the third side surface is formed, and a first parallel flat plate portion is formed in each flat plate portion including the second side surface and the fourth side surface, and a free end side of the elastic metal is formed. Is formed with a through hole penetrating from the second side surface to the fourth side surface, a second parallel flat plate portion is formed by each flat plate portion including the first side surface and the third side surface, and a first parallel flat plate portion is formed. Ferroelectric films are formed on the two side surfaces and the fourth side surface and on the first side surface and the third side surface of the second parallel plate portion, respectively, and the same ferroelectric film is formed on each ferroelectric film of the second parallel plate portion. A first electrode and a second electrode are provided respectively corresponding to portions that are inversely deformed when the dielectric film expands and contracts, and an electrode is provided on each ferroelectric film of the first parallel plate portion. The gist is a parallel plate vibrating gyroscope.

According to a second aspect of the present invention, in the first aspect, on each of the ferroelectric films of the first parallel plate portion, the ferroelectric films correspond to portions which are inversely deformed when the ferroelectric film is expanded and contracted. The gist of the present invention is a parallel plate vibrating gyroscope provided with a third electrode and a fourth electrode.

The third aspect of the present invention is the first or second aspect.
In the above, the first electrode and the second electrode are characterized by a parallel plate type vibrating gyroscope disposed on a ferroelectric thin film corresponding to a point of maximum stress concentration at the time of deformation in an elastic metal.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the second side surface and the fourth side surface of the first parallel plate portion and the first side surface and the third side surface of the second parallel plate portion are provided. A base surface made of titanium is formed on the side surface, and the ferroelectric thin film has a parallel plate vibrating gyroscope as a PZT thin film formed on the base surface.

According to a fifth aspect of the present invention, there is provided an apparatus provided with the parallel plate type vibrating gyroscope according to the second aspect, wherein the oscillation circuit outputs an oscillation signal at a predetermined frequency, and the first oscillation circuit inverts the oscillation signal. An inverting circuit for applying a voltage signal based on the oscillation signal to each of the third electrodes on the second side surface and the fourth side surface of the parallel plate portion, and a second side surface and a second portion of the first parallel plate portion without inverting the oscillation signal. A non-inverting circuit for applying a voltage signal based on the oscillation signal to each of the fourth electrodes on the four side surfaces, and a detection signal from the first electrode on the first side surface and the second electrode on the third side surface of the second parallel plate portion; A first differential circuit that takes a difference and outputs a signal related to a difference between the detection signals of the two electrodes, and a detection signal of a detection signal from the second electrode on the first side surface and the first electrode on the third side surface of the second parallel plate portion. A second differential circuit for taking a difference and outputting a signal relating to the difference between the detection signals of the two electrodes; It adds both signals from the dynamic circuit and the second differential circuit, it is an gist parallel plate type vibration gyro apparatus and an adding circuit for outputting the addition result. (Function) According to the first aspect of the invention, in the second parallel flat plate portion serving as the vibration gyro detection unit, the second parallel flat plate portion has the same strength on the ferroelectric films on the first side surface and the third side surface. Since the first electrode and the second electrode are respectively provided corresponding to portions that are inversely deformed when the dielectric film expands and contracts, a piezoelectric signal due to the expansion of the ferroelectric film is provided at each electrode.
And a piezoelectric signal due to shrinkage is obtained.

According to the second aspect of the present invention, in the first parallel flat plate portion serving as the driving unit of the vibrating gyroscope, the first parallel flat plate portion is provided on the second side surface and the fourth side surface of the ferroelectric film. Since the third electrode and the fourth electrode are respectively provided corresponding to portions that are deformed in opposite directions when the ferroelectric film expands and contracts, alternating voltages of opposite polarities are provided through the respective electrodes. By applying the voltage, the first parallel plate portion can be vibrated.

According to the third aspect of the present invention, when the first electrode and the second electrode are arranged on the ferroelectric thin film corresponding to the maximum stress concentration place at the time of deformation in the elastic metal, the maximum stress concentration place is: Since the largest expansion and contraction occur, the obtained piezoelectric voltage is also large.

According to the fourth aspect of the present invention, the second side surface and the fourth side surface of the first parallel plate portion and the first side surface of the second parallel plate portion.
4. The base according to claim 1, wherein a base surface made of titanium is formed on the side surface and the third side surface, and the ferroelectric thin film is a PZT thin film formed on the base surface. The operation described in any one of them is realized.

According to the fifth aspect of the present invention, the oscillation circuit outputs an oscillation signal at a predetermined frequency. The inverting circuit inverts the oscillation signal, and the second side surface and the fourth side surface of the first parallel plate portion.
It is applied to each third electrode on the side. The non-inverting circuit applies the oscillation signal to each of the fourth electrodes on the second and fourth side surfaces of the first parallel plate portion without inverting the oscillation signal. As a result, the first parallel flat plate portion that is the driving unit vibrates.

When the parallel plate type gyro rotates around the axis when the first parallel plate portion vibrates, the first differential circuit includes a first electrode on the first side surface of the second parallel plate portion and a third electrode. The difference between the detection signals from the second electrode on the side surface is obtained, and a signal related to the difference between the detection signals from both electrodes is output. On the other hand, the second differential circuit obtains a difference between detection signals from the second electrode on the first side surface of the second parallel plate portion and the first electrode on the third side surface, and outputs a signal related to the difference between the detection signals from both electrodes. Output. The addition circuit adds the two addition signals from the first differential circuit and the second differential circuit, and outputs the addition result.

[0025]

FIG. 1 to FIG. 9 show an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a perspective view of the vibrating gyroscope 1. In addition, the thickness of the titanium film, the electrode film, and the side plate illustrated in each drawing including the above-described drawing are appropriately enlarged from actual ones for convenience of description.

As shown in FIG. 1, the vibrating gyroscope 1 has a quadrangular prism shape, and has parallel plate portions 3 and 2 provided on the upper and lower sides. The parallel plate portions 3 and 2 correspond to the second and first parallel plate portions of the present invention, respectively.

As shown in FIG. 1, the base 4 of the vibrating gyroscope 1 is made of stainless steel as an elastic metal forming a quadrangular prism. Note that, in the present embodiment, the cross section of the base material 4 has a square shape. The cross-sectional shape of the substrate 4 is preferably a square, but is not necessarily limited to a square. The substrate 4 has a first side surface 5 facing the X direction.
And the second side surface 6 in the clockwise direction (circumferential direction),
The third side surface 105 and the fourth side surface 106 are arranged in this order (see FIG. 2).

The parallel plate type vibrating gyroscope 1 shown in FIG. 2 is a schematic diagram. For convenience of explanation, the parallel plate portion 2 and the parallel plate portion 3 are shown in a state of being rotated by 90 ° relative to each other. The first side surface 5 and the second side surface 6 are shown to face in the same direction.

The first side face 5 and the third side face 105
It is located 180 degrees on the opposite side about the Z axis, and
The side surface 6 and the fourth side surface 106 are also located on the opposite side by 180 degrees about the Z axis (only the first side surface 5 and the second side surface 6 are shown in FIG. 1).

The first side surface 5 at the lower part of the substrate 4 and the third side surface 1
Reference numeral 05 denotes a through-hole 7 having a rectangular cross section directed in the X-axis direction.
Are drilled. A pair of side plates 8 and 9 having the second side surface 6 and the fourth side surface 106 as outer surfaces are formed at the lower portion of the base 4 by the through holes 7. The side plates 8, 9 correspond to flat plate portions. The side plates 8 and 9 are thin portions 8a and 9a having a thickness of several tens to several hundreds μm. The lower portion of the base member 4 has a parallel plate structure in which the lower portions of the base member 4 are arranged in parallel with each other by the side plates 8 and 9 and the through hole 7, thereby forming the parallel plate portion 2.

The second side surface 6 and the fourth side surface 106 on the upper portion of the base member 4 are provided with through holes 10 each having a rectangular cross section directed in the Y-axis direction. A pair of side plates 11 and 12 having the first side surface 5 and the third side surface 105 as outer surfaces are formed at the upper portion of the base material 4 by the through holes 10. The side plates 11, 12 correspond to flat plate portions. The side plates 11 and 12 have a thin portion 1 having a thickness of several tens to several hundreds μm.
1a and 12a. The side plates 11 and 12 correspond to the flat portion of the present invention. The thickness of the side plates 11 and 12 is as follows:
It has the same thickness as the side plates 8 and 9 of the parallel plate portion 2. The upper side of the base material 4 has a parallel plate structure arranged in parallel with each other by the side plates 11 and 12 and the through hole 10, thereby forming the parallel plate portion 3.
The parallel plate portions 2 and 3 are arranged to be orthogonal to each other.

The titanium film 13 is formed on the second side surface 6 and the fourth side surface 106 in the parallel plate portion 2 and on the first side surface 5 to the third side surface 105 in the parallel plate portion 3 by sputtering or the like (see FIG. 1). (See FIG. 5). The titanium film 13 forms a base surface. Titanium film 1
3 is a PZT thin film 14 having a thickness of several tens of μm (FIG. 6).
Reference) is formed. The PZT thin film 14 forms a ferroelectric film.

As shown in FIG. 2, on the PZT thin film 14 on the first side face 5 and the third side face 105 of the parallel plate portion 3, a first electrode film made of aluminum and having the same area and having a thickness of several μm is formed. 15, a pair of second electrode films 16 is formed in the vertical direction (only the first side surface 5 is shown in FIG. 1). On the first side surface 5, the first electrode film 15 and the second electrode film 16 are arranged vertically. Also, on the third side surface 105, the first electrode film 15
Are disposed on the lower side, and the second electrode film 16 is disposed on the upper side (see FIG. 2).

For example, when the parallel plate portion 3 is deformed into a waveform to the right as shown in FIG. 7, the upper side of the PZT thin film 14 on the first side surface 5 in the parallel plate portion 3 expands and the lower side contracts. . On the other hand, the upper side of the PZT thin film 14 on the third side surface 105 contracts and the lower side extends. A first electrode film 15 and a second electrode film 16 are arranged corresponding to the portions where the expansion and contraction occur. In FIG. 7, in the PZT thin film 14, the arrows indicate the polarization direction of the PZT thin film 14, the hatched portion on the lower right indicates the extending portion, and the hatched portion on the lower left indicates the contracted portion.

The second side surface 6 of the parallel plate portion 2
On the PZT thin film 14 on the fourth side surface 106, a third electrode film 17 and a fourth electrode film 18 having a thickness of several μm and made of aluminum and having the same area are formed in a vertical direction (FIG. 1). Indicates only the second side surface 6). Second
On the side surface 6, the third electrode film 17 and the fourth electrode film 18 are arranged vertically. On the fourth side surface 106, the third electrode film 17 is located on the lower side, opposite to the second side surface 6.
The electrode film 18 is disposed on the upper side (see FIG. 2).

This is because, when voltages of opposite polarities are applied to the respective electrode films 17 and 18 of the PZT thin film 14 of the parallel plate portion 2, the portions applied by the third electrode film 17 and the fourth electrode film The portions applied to the film 18 are for causing the same deformation (elongation or contraction). By doing so, a large deformation can be efficiently applied to the parallel flat plate portion 2 which is a driving portion.

The first to fourth electrode films 15 to 18
Correspond to the first to fourth electrodes, respectively. In this embodiment, the lower end of the vibrating gyroscope 1 corresponds to the fixed end, and the upper end corresponds to the free end. And the parallel plate part 2 comprises a drive part, and the parallel plate part 3 comprises a detection part.

Next, a method of manufacturing the vibrating gyroscope 1 will be described with reference to FIGS. FIG. 3 shows the substrate 4. The base material 4 made of stainless steel is formed in a quadrangular prism shape having a square cross section. The upper and lower portions of the base material 4 are inserted through the through holes 7 and 1 so as to be orthogonal to each other.
0 is formed. The formation of the through holes 7 and 10 may be performed by cutting or etching. By forming the through holes 7, the lower surface of the base member 4 has the second side surface 6 and the fourth side surface 106 as outer surfaces, respectively, as shown in FIG. A pair of side plates 8 and 9 are formed. The parallel plate portion 2 having a parallel plate structure in which the side plates 8 and 9 are arranged in parallel with each other is formed below the base member 4 by the side plates 8 and 9 and the through hole 7.

Further, by forming the through holes 10, the upper portion of the base member 4 is formed on the first side face 5 and the third side face 5 as shown in FIG.
Each of the side surfaces 105 is an outer surface, and a pair of side plates 11 and 12 having a plate thickness of several tens to several hundreds μm are formed. or,
The parallel plate portion 3 having a parallel plate structure in which the side plates 11 and 12 are arranged in parallel with each other is formed on the upper portion of the base material 4 by the side plates 11 and 12 and the through hole 10.

Next, the base material 4 is cleaned with an acid or the like, and the surface excluding the side surface on which the PZT thin film 14 is to be formed is removed with a synthetic resin or a physical film forming method such as sputtering or vacuum deposition. A mask (not shown) is formed by coating with a metal other than titanium or the like.

The second side surface 6 in the parallel plate portion 2 of the substrate 4
Then, the titanium film 13 is formed on the first side surface 5 and the third side surface 105 in the fourth side surface 106 and the parallel plate portion 3 by a physical film forming method such as sputtering or vacuum evaporation (see FIG. 5).

Next, a PZT thin film 14 is formed on the titanium film 13 by a hydrothermal method. This hydrothermal method consists of two stages. (First step) substrate 4, zirconium oxychloride as a raw material (ZrOCl ₂ · 8H ₂ O) and lead nitrate (Pb (N
An aqueous solution of O ₃ ) ₂ ) and a KOH (8N) solution are charged into a Teflon bottle (not shown) and stirred. In addition, PZT
Since the piezoelectricity of the thin film 14 is determined by the composition ratio of lead titanate and lead zirconate in the PZT thin film 14, if the molar ratio between zirconium oxychloride and lead nitrate is determined according to the piezoelectricity of the PZT thin film 14 to be formed later. Good.

Next, in a pressure vessel (not shown), the base material 4 is disposed above, and zirconium oxychloride (ZrO 2
Cl ₂ · 8H ₂ O), an aqueous solution of lead nitrate _{(Pb (NO 3) 2)} , and while stirring KOH (8N) solution, heating and
Apply pressure. The pressurization here is pressurization by the vapor pressure of the heated solution. Temperature condition is 150 ° C
This state is continued for 48 hours. In addition, stirring was performed for 30 minutes.
Perform at 0 rpm.

As a result, in the supersaturated state, seed crystals (nuclei) of PZT are formed on the surfaces of the titanium films 13 of the two parallel flat plate portions 2 and 3 of the substrate 4. After the elapse of the above time, the substrate 4 is taken out of the pressure vessel, washed with water and dried.

(Second Step) Next, the substrate 4 on which seed crystals are nucleated, and zirconium oxychloride (Z
rOCl ₂ · 8H ₂ O) and lead nitrate (Pb (NO _{3) 2)}
Aqueous solution, titanium tetrachloride (TiCl ₄ ) and KOH (4
N) Put the solution in a Teflon bottle (not shown) and stir. Since the piezoelectricity of the PZT thin film 14 is determined by the composition ratio of lead titanate and lead zirconate in PZT, the molar ratio of zirconium oxychloride, titanium tetrachloride, and lead nitrate depends on the piezoelectricity of PZT to be formed later. You can decide.

Next, in a pressure vessel (not shown), the substrate 4 is placed above and zirconium oxychloride (ZrO 2
Cl ₂ · 8H ₂ O), an aqueous solution of lead nitrate _{(Pb (NO 3) 2)} , titanium tetrachloride (TiCl ₄₎ and KOH (4N)
Heat and pressurize while stirring the solution. The pressurization here is pressurization by the vapor pressure of the heated solution. The temperature condition is 120 ° C., and this state is maintained for 48 hours. The stirring is performed at 300 rpm.

As a result, in the supersaturated state, the PZT thin film 14 is formed with a predetermined thickness (several tens of μm in this embodiment) on both outer surfaces of the two parallel flat plate portions 2 and 3 of the substrate 4 (see FIG. 6). . After the elapse of the above time, the substrate 4 is taken out of the pressure vessel, washed with water and dried. Thereafter, the mask is removed.

Then, after aluminum is formed on the surface of the PZT thin film 14 by a physical film forming method such as sputtering or vacuum evaporation, patterning is performed, and unnecessary portions are removed.
A pair of upper and lower electrode films 15, 16, 17, 18 is formed to form the vibrating gyroscope 1. Thereafter, a lead wire is soldered to the pad portion on the electrode film.

Next, a vibration gyro device 41 employing the above-described vibration gyro 1 will be described with reference to FIG. The vibration gyro device 41 includes an oscillation circuit 42. The oscillating circuit oscillates a voltage signal of a predetermined frequency and outputs it to an inverting amplifier circuit 43 and a non-inverting amplifier circuit. The inverting amplification circuit 43 inverts and amplifies the input voltage signal, and applies the inverted and amplified voltage signal to the third electrode film 17 of the vibrating gyroscope 1. Further, the non-inverting amplifier circuit 44 amplifies the input voltage signal and applies the amplified voltage signal to the fourth electrode film 18 of the vibrating gyroscope 1. The inverting amplifier 43 constitutes an inverting circuit. The non-inverting amplifier circuit 44 forms a non-inverting circuit.

The base 4 of the vibrating gyroscope 1 is grounded. In the parallel plate portion 3 serving as the detection portion, one of the first electrode film 15 and the second
The electrode film 16 is electrically connected to a differential circuit 45 that is a first differential circuit. The differential circuit 45 includes the first electrode film 1
5 and the second electrode film 16 and the like, the difference is taken, and a doubled piezoelectric signal is obtained.
Output to

The other first electrode film 15 and second electrode film 16 provided on opposite sides are electrically connected to a differential circuit 46 as a second differential circuit. The differential circuit 46 receives the piezoelectric signals and the like input from the first electrode film 15 and the second electrode film 16, takes the difference, and outputs the difference to the adding circuit 47 as a doubled piezoelectric signal.

The adder circuit 47 includes two differential circuits 45, 4
The doubled piezoelectric signals input from 6 are added with their polarities aligned, and output as quadrupled piezoelectric signals. When the vibrating gyro device 41 configured as described above is used, the oscillation circuit 42 and the inversion circuit are applied to the electrode films 17 and 18 of the parallel plate portion 2 with the lower end of the substrate 4 fixed. The amplifying circuit 43 and the non-inverting amplifying circuit 44 apply alternating voltages of opposite potentials in synchronization with each other.

When the polarization direction of the PZT thin film 14 is directed from the electrode films 17 and 18 toward the substrate 4, the PZT thin film 14 applied to the positive potential side is compressed and applied to the negative potential. The side PZT thin film 14 is stretched. And by the change of polarity due to the alternating voltage,
The PZT thin film 14 on the second side surface 6 has the third
The PZT thin film 14 on the back side of the electrode film 17 and the fourth electrode film 18 and the PZT thin film 14 on the fourth side surface 106 are compressed and stretched on the back side of the fourth and third electrode films 18 and 17 arranged vertically. Are alternately repeated.

As a result, the parallel plate portion 2 is driven in the Y and anti-Y directions, and the upper parallel plate portion 3 vibrates in the same direction. Then, in this vibration state, the vibration gyro 1
When the rotation of the angular velocity ω is applied around the axis, the PZT thin film 14 on one side surface of the parallel plate portion 3 is compressed (strained), and the other side surface (one side is 180 °).
The opposite side) is stretched (distorted).

At this time, as shown in FIG.
Is deformed to the right side, the upper side of the PZT thin film 14 on the first side surface 5 in the parallel plate portion 3 expands and the lower side contracts. On the other hand, the upper side of the PZT thin film 14 on the third side surface 105 contracts and the lower side extends. A first electrode film 15 and a second electrode film 15 arranged corresponding to respective portions where the expansion and contraction occur.
The electrode film 16 outputs a piezoelectric signal or the like generated on the PZT thin film 14 to the differential circuit 45 and the differential circuit 46 at that time.

The signals output from the electrode films 15 and 16 include, as components other than the piezoelectric signal, the leakage of the input signal (voltage signal from the inverting amplifier circuit 43 and the non-inverting amplifier circuit 44), And noise.

That is, for example, the first electrode film 15 is formed by compression (shrinkage) or tension (elongation) of the PZT thin film 14.
Let G1 be the signal (detection signal) output from the PZT thin film 14, G1 = leakage of the input signal M + noise N−piezoelectric signal A (+ and − of the piezoelectric signal A are opposite depending on the polarization direction of the PZT thin film 14). Become).

At this time, a signal (detection signal) output from the second electrode film 16 is represented by G2 due to compression (shrinkage) or tension (elongation) of the PZT thin film 14 which operates in the opposite direction to the first electrode film 15. Then, G2 = leakage of input signal M + noise N + piezoelectric signal A.

In the differential circuits 45 and 46, the first electrode film 15
The difference between the output signal from the second electrode film 16 and the output signal from the second electrode film 16 (G2−G1) is obtained, so that the output signals from the differential circuits 45 and 46 are equal to the piezoelectric signal A twice as large as the piezoelectric signal A. Become.

The addition circuit 47 includes the two differential circuits 4
Since the doubled piezoelectric signal A from 5, 46 is further added with the same polarity, a piezoelectric signal four times the piezoelectric signal A is obtained. As a result, it becomes possible to detect the Coriolis force acting on the vibrating gyroscope 1. Further, as shown in the above equation (1), if the mass m and the vibration velocity V of the vibration gyro 1 are known, the angular velocity ω can be derived.

According to the present embodiment, the following operation and effect can be obtained. (1) The generated voltage (piezoelectric signal) A when a force F is applied to the PZT thin film 14 in the present embodiment will be described.

FIG. 9 shows a PZT having a film thickness d, a length L and a width W.
A thin film is shown. When a force of F is applied to the PZT thin film in the length direction, the length L becomes L-ΔL. At this time, the opposite upper and lower sides of the PZT thin film have + ΔQ and −ΔQ depending on the polarization direction. Charge is generated. Therefore, the generated voltage A at this time is given by the following equation.

A = ΔQ / C (C is electric capacity) At this time, C = (S · εo · εr) / d (εo is a vacuum permittivity, εr is a relative permittivity of the PZT thin film, and S (area of the PZT thin film) ) = W × L), so that A = (ΔQ · d) / (S · εo · εr). From this, V can be increased as the area of the electrode (electrode film) is smaller.

Accordingly, in the present embodiment, the first electrode film 15 and the second electrode film 1
6, the area of the electrode film is made smaller than before, so that the piezoelectric voltage A can be increased.

(2) In the vibrating gyroscope 1 of the present embodiment, the first electrode film 15 and the second electrode film 16 are vertically arranged on the first side surface 5, and
Contrary to the first side face 5, the first electrode film 15 is disposed on the lower side, and the second electrode film 16 is disposed on the upper side (see FIG. 2). That is, for example, when the parallel plate portion 3 is deformed into a waveform to the right as shown in FIG. 7, the PZT on the first side surface 5 of the parallel plate portion 3 is formed.
The upper side of the thin film 14 expands and the lower side contracts. On the other hand, the third side 1
The upper side of the PZT thin film 14 on the upper side 05 contracts and the lower side extends.
The first corresponding to each part where this elongation / contraction occurs
The electrode film 15 and the second electrode film 16 were arranged.

As a result, the PZT at each site
Piezoelectric signals corresponding to the expansion and contraction of the thin film 14 can be obtained. (3) In the vibrating gyroscope 1 of the present embodiment, the third electrode film 17 is formed on the second side surface 6 of the parallel plate portion 2.
And the fourth electrode film 18 are arranged vertically. Then, on the fourth side surface 106, the third electrode film 1 is opposite to the second side surface 6.
7 was arranged on the lower side, and the fourth electrode film 18 was arranged on the upper side (see FIG. 2).

When voltages having opposite polarities are applied to the respective electrode films 17 and 18 of the PZT thin film 14 of the parallel plate portion 2, for example, shrinkage occurs at the portion applied by the third electrode film 17. And elongation deformation occurs in the portion where the fourth electrodeless film 18 is applied. Conversely, when the portion applied by the third electrode film 17 is elongated, the portion applied by the fourth electrode film 18 is contracted. in this way,
On the opposing side surfaces, the third electrode film 17 and the fourth electrode film 18 are provided correspondingly at the opposing portions, and one extends at the opposing portions and the other shrinks, so that the parallel portions, which are the driving portions, are formed. Large deformation can be efficiently applied to the flat plate portion 2.

(4) Vibrating gyroscope device 4 of the present embodiment
In FIG. 1, one of the first electrode film 15 and the second
The electrode film 16 was electrically connected to a differential circuit 45 as a first differential circuit. The differential circuit 45 includes the first electrode film 15
Then, the difference between the piezoelectric signal and the like input from the second electrode film 16 is obtained and output to the adding circuit 47 as a doubled piezoelectric signal.

The other first electrode film 15 and second electrode film 16 provided on the opposite sides are electrically connected to a differential circuit 46 as a second differential circuit. 46
Calculates the difference between the piezoelectric signals and the like input from the first electrode film 15 and the second electrode film 16 and converts the difference into a doubled piezoelectric signal.
7 output.

The adder circuit 47 includes two differential circuits 45, 4
The two-fold piezoelectric signal input from No. 7 is added in a state where the polarities thereof are aligned, and the resultant signal is output as a four-fold piezoelectric signal.
As a result, a large output can be obtained as the piezoelectric signal of the vibration gyro device 41, and the detection sensitivity can be increased.

(5) In this embodiment, since the PZT thin film 14 formed on the surface of the titanium film 13 of the two parallel flat plate portions 2 and 3 of the base material 4 is formed as thin as several tens μm, the vibration gyro 1 Can be reduced in size.

(6) In the present embodiment, since the upper and lower portions of the base material 4 have a parallel plate structure, it is possible to make the base material 4 resistant to twisting. Accordingly, the vibration driving parallel plate portion 2 can accurately vibrate, and the detection parallel plate portion 3 can be accurately displaced, so that it is strong against noise.

(7) In the present embodiment, the hydrothermal method
A titanium film 13 is formed on both outer surfaces of the two parallel flat plate portions 2 and 3 of the substrate 4
Is formed, a PZT thin film 14 is formed by a hydrothermal method, and then, on both side surfaces of the base material 4 on which the PZT thin film 14 is formed, electrode films 15, 16, 17, and 18, respectively.
Was formed. As a result, the same process (process by hydrothermal method)
The vibration gyro 1 composed of the combination of the vibration driving parallel flat plate portion 2 and the detection parallel flat plate portion 3 obtained in the step (1) should have uniform quality such as detection sensitivity, that is, be uniform. it can. Also, the driving PZT thin film 1 is formed by a hydrothermal method.
4 and the PZT thin film 14 for detection can be formed at one time, so that the number of manufacturing steps can be reduced unlike the case where the PZT thin films for driving and detection are separately formed.

(8) Side plate 11 of parallel plate portion 3 for detection
The connecting part connecting the upper part of the side plate 12 and the connecting part of the part between the parallel plate part 2 and the parallel plate part 3 is used as the mass m of the Coriolis force Fc of the above formula (1). it can. Therefore, it is possible to adjust m of the vibrating gyroscope 1 by appropriately changing the mass of the same portion. Thereby, the detection sensitivity of the vibrating gyroscope 1 can be increased.

The embodiment of the present invention can be modified as follows in addition to the above embodiment. (1) In the above embodiment, the electrode films 15 and 16 are made of PZT
The electrode film 1 is provided corresponding to the compressed / shrinked portion of the thin film 14, but corresponds to the portion where the maximum stress of the base material 4 is concentrated (the maximum stress concentration portion) as shown by the dashed line in FIG.
5 and 16 may be provided.

By doing so, a large strain is generated in the PZT thin film 14 due to expansion and contraction in the maximum stress concentration portion of the parallel plate portion 3 which is the detection portion, so that a large piezoelectric voltage can be obtained.

(2) In the above embodiment, the electrode films 15 to
Although 18 is formed of aluminum, it may be formed of Au (gold) or may be formed of another conductive metal. (3) In the above embodiment, the thickness of the electrode films 15 to 18 PZT thin film 14 and the thickness of the base material 4 are each set to a predetermined numerical value. However, the present invention is not limited to the above numerical values. Good.

(4) In the above embodiment, the PZT thin film 1
The electrode films 15 to 18 were formed on the four surfaces by a physical film forming method such as sputtering or vacuum deposition and then patterned. Instead, these were formed by printing a conductive paste by a screen printing method. Is also good.

(5) In the above embodiment, the vibrating gyroscope 1 is embodied as a resonator element. However, the vibrating gyroscope 1 may be embodied as a vibrating gyroscope of a tuning fork type fixed to both ends of a connecting plate. In this case, a tuning fork-type vibrating gyroscope can be formed only by erection and fixing the pair of vibrating gyroscopes 1 in the above embodiment to both ends of a connecting plate as a connecting portion.

(6) In the above embodiment, the lower end of the vibrating gyroscope 1 is a fixed end, but the upper end may be a fixed end and the lower end may be a free end. In this case, the drive unit is the upper end and the detector is the lower end.

(7) In the above embodiment, the substrate 4 is made of stainless steel. However, other metals may be used. When titanium is used, the formation of the titanium film 13 becomes unnecessary. In this case, the surface of the substrate 4 constitutes the base surface of the present invention.

Here, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below together with their effects. (1) The parallel plate vibrating gyroscope according to any one of claims 1 to 4, wherein the through-hole has a rectangular cross section. The side walls of the first and second parallel flat plate portions are formed in a plate shape by the through holes having a square cross section, so that a parallel flat plate structure can be obtained.

[0083]

As described above in detail, according to the first aspect of the present invention, when the parallel plate portion serving as the detecting portion is deformed, even if the expansion and contraction are reversed at the side portions of the parallel plate portion, the generated voltage is not changed. Are not canceled out, and a large piezoelectric signal can be obtained. According to the second aspect of the present invention, in the first parallel flat plate portion serving as the driving unit of the vibrating gyroscope, the second parallel flat plate portion is provided with the second parallel flat plate portion.
A third electrode and a fourth electrode are provided on the ferroelectric films on the side surface and the fourth side surface, respectively, so as to correspond to portions that are deformed in opposite directions when the ferroelectric film expands and contracts. By applying alternating voltages of opposite polarities through the electrodes, the first parallel flat plate portion can be vibrated.

According to the third aspect of the present invention, when the first electrode and the second electrode are disposed on the ferroelectric thin film corresponding to the location of the maximum stress concentration at the time of deformation of the elastic metal, the parallel plate serving as the detecting section In the portion where the maximum stress is concentrated, a large strain is generated in the ferroelectric thin film due to expansion and contraction, so that a large piezoelectric voltage can be obtained.

According to the fourth aspect of the present invention, the second side surface and the fourth side surface of the first parallel plate portion and the first side surface and the third side surface of the second parallel plate portion are formed of titanium. A surface is formed, and the ferroelectric thin film is a PZT thin film formed on the base surface, thereby obtaining the effect according to any one of claims 1 to 3.

According to the fifth aspect of the present invention, the vibration gyro device can have higher detection sensitivity by a circuit configuration.

[Brief description of the drawings]

FIG. 1 is a perspective view of a parallel plate vibrating gyroscope according to an embodiment.

FIG. 2 is an electric circuit of a parallel plate type vibration gyro device.

FIG. 3 is a perspective view of a base material.

FIG. 4 is a perspective view of a base material in which a through hole is formed.

FIG. 5 is a perspective view of a base material formed by patterning a titanium film.

FIG. 6 is a perspective view of a substrate on which a PZT thin film is formed.

FIG. 7 is a schematic diagram for explaining the operation of the parallel plate vibrating gyroscope.

FIG. 8 is a schematic view for explaining the operation of the parallel plate vibrating gyroscope.

FIG. 9 is an explanatory diagram for explaining a generated voltage.

FIG. 10 is a perspective view of a conventional vibrating gyroscope.

FIG. 11 is a sectional view of a main part of a vibrating gyroscope.

FIG. 12 is a schematic view showing the operation of a vibrating gyroscope.

FIG. 13 is a perspective view of a conventional vibrating gyroscope.

FIG. 14 is a perspective view of a conventional vibrating gyroscope.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vibration gyroscope 2, 3 ... Parallel plate part (1st, 2nd parallel plate part is comprised), 4 ... Base material (elastic metal), 5 ... 1st side surface, 6 ... 2nd side surface,
Reference numeral 105: third side surface, 106: fourth side surface, 7, 10, through hole, 8, 9, 11, 12, side plate (constituting a flat plate portion), 13: titanium film (constituting a base surface), 14 ... PZT thin film (constituting a ferroelectric film. 15) first electrode film (constituting a first electrode), 16 ... second electrode film (constituting a second electrode), 17 ... third electrode Film (constituting a third electrode), 18: fourth electrode film (constituting a fourth electrode), 41: vibrating gyro device, 42: oscillation circuit, 43: inverting amplifier circuit (constituting an inverting circuit) 44, a non-inverting amplifier circuit (constituting a non-inverting circuit); 45, a differential circuit (constituting a first differential circuit); 46, a differential circuit (constituting a second differential circuit). , 47 ...
Addition circuit.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshio Fukuda 2-66, Yadacho, Higashi-ku, Nagoya-shi Naoya Tamachi Dormitory No. 122 (72) Inventor Koichi Itoigawa 1 Noda, Toyota, Oita-cho, Oguchi-cho, Niwa-gun, Aichi Prefecture Shares (72) Inventor Hitoshi Iwata Oita-machi, Niwa-gun, Aichi Prefecture 1-Toyota Noda 1 Tokai-Rika Electric Machinery Co., Ltd.

Claims (5)

[Claims] The first to fourth side surfaces (5, 5) extend in the circumferential direction.
6, 105, 106), and the first side surface (5) and the third side surface (105), and the second side surface (6) and the fourth side surface (106) are located 180 degrees opposite to each other in a quadrangular prism shape. A first side surface (5) on the fixed end side of the elastic metal (4).
A through hole (7) penetrating from the first side to the third side (105) is formed, and the first parallel flat part (2) is formed by a flat part including the second side (6) and the fourth side (106). A second side surface (6) is formed on a free end side of the elastic metal (4).
A through hole (10) penetrating from the first side surface to the fourth side surface (106) is formed, and the second parallel flat plate portion (3) is formed by a flat plate portion including the first side surface (5) and the third side surface (105). The second side surface (6) and the fourth side surface (1) of the first parallel plate portion (2) are formed.
06) and the first side surface (5) and the third side surface (105) of the second parallel plate portion (3), respectively.
4) is formed, and on each of the ferroelectric films (14) of the second parallel plate portion (3), the ferroelectric films (14) correspond to portions which are inversely deformed when the ferroelectric films (14) expand and contract. A first electrode (15) and a second electrode (16) are provided, and an electrode (1) is provided on each ferroelectric film (14) of the first parallel plate portion (2).
7, 18) are provided, respectively. 2. The first ferroelectric film (14) of the first parallel plate portion (2) corresponds to portions which are inversely deformed when the ferroelectric film (14) expands and contracts. The parallel plate vibrating gyroscope according to claim 1, wherein a third electrode (17) and a fourth electrode (18) are provided. 3. The first electrode (15) and the second electrode (1).
The parallel plate according to claim 1 or 2, wherein the elastic metal (4) is disposed on the ferroelectric thin film (14) corresponding to a maximum stress concentration point during deformation in the elastic metal (4). Type vibration gyro. 4. A second side (6) and a fourth side (106) of the first parallel plate portion (2) and a first side (5) and a third side (3) of the second parallel plate portion (3). 105), a base surface (13) made of titanium is formed, and the ferroelectric thin film (14) is a PZT thin film formed on the base surface (13). Item 4. A parallel plate vibrating gyroscope according to any one of Items 3. 5. An apparatus provided with the parallel plate vibrating gyroscope according to claim 2, wherein the oscillation circuit outputs an oscillation signal at a predetermined frequency.
And the third electrode (17) on the second side surface (6) and the fourth side surface (106) of the first parallel plate portion (2).
An inverting circuit (43) for applying a voltage signal based on the oscillation signal to each of the second side surface (6) and the fourth side surface (106) of the first parallel plate portion (2) without inverting the oscillation signal. A non-inverting circuit (44) for applying a voltage signal based on the oscillation signal to the fourth electrode (18); and a first electrode (1) on the first side surface (5) of the second parallel plate portion (3).
5) and a first differential circuit (45) for taking the difference between the detection signals from the second electrode (16) on the third side surface (105) and outputting a signal related to the difference between the detection signals from both electrodes; The second electrode (1) on the first side surface (5) of the parallel plate portion (3)
6) and a second differential circuit (46) for taking a difference between the detection signals from the first electrode (15) on the third side surface (105) and outputting a signal related to the difference between the detection signals from both electrodes; A parallel plate vibrating gyroscope comprising an adder circuit (47) for adding both signals from one differential circuit (45) and a second differential circuit (46) and outputting the addition result.